Sweeping Debris Disposal

Deciding When Power Sweeping Debris is Dangerous

Washington State's Department of Ecology releases its 'straw dog' draft on best management practices.

The Washington State Department of Ecology recently sent out what it termed a 'straw dog' draft of a 20+ page report it had prepared entitled Best Management Practices (BMPs) For Management and Disposal of Street Wastes. The draft, whose purpose was to "outline ways of street waste treatment, disposal and reuse that are economic, preserve resources, and protect human health and the environment," was designed to solicit comments and suggestions from the sweeping industry. We interviewed Michael Hepp, R.P.G., Ecology Hydrogeologist, and contact for the study:

World Sweeper: What motivated Ecology to put out a report on this topic?

Hepp: Cleaning streets and storm sewers is part of our current efforts to prevent water pollution from storm water. The fact is that if we're going to clean it up then we need a place to put it. What we have seen is that this stuff is extremely variable. Street sweeping is probably worse for its variability, but in the end it is still not going to be dangerous waste by our state definition of dangerous waste.

World Sweeper: Which means low concentrations of heavy metals or what?

Hepp: Dangerous waste is a legal distinction for solid waste that is toxic. It actually means that it would be dangerous to carry or transport it, or to put it into a landfill. Landfills were not really made for dangerous waste and that is the basis for their definition. If it is not dangerous waste then it becomes what is called solid waste. And solid waste is everything else except for recyclable items, such as cans, that can be physically separated out.

World Sweeper: In the current opinion of Ecology should there be another category, some sort of middle ground? Or is your initial conclusion that street sweepings, by and large, fit the classification of solid waste?

Hepp: It is solid waste, but there are some recycling possibilities for it. As variable as street sweeping waste is, if it doesn't look bad or hasn't been bad in the past with random sampling, it isn't going to be dangerous waste. Therefore it is solid waste, and the least expensive place for solid waste is usually a sanitary landfill. They're made for handling this.

World Sweeper: How about use as landfill cover?

Hepp: It works in places and doesn't in others. In Portland [Oregon] it doesn't, because it contains too many fines. It won't compact well enough and litter tends to blow around. Up here they seem to be happy with it. I have two basic tenets to the street waste guidance. One is that you don't give it to anybody without them knowing its origin and accepting it as such. The second is you do a screening before you pick it up to see if there are signs that contamination might have taken place. As examples, has there been a spill here before; does it look like there has been a spill of some type since the last time it was swept; is the area one of heavy industry with a history of problems? Only after that sort of rudimentary ecision-making has taken place do you get into the guidance we have set up.

World Sweeper: Word is that some landfills are charging a premium for street waste. In at least some cases this is not based upon testing or any other objective criteria, but seemingly because the operators think they can get the extra money. It is very subjective - landfill to landfill. It would be much better if there were some sort of national criteria of safety that street and parking lot sweepings could be put into.

Hepp: Each landfill has its requirements...I think that landfill disposal is the most likely use for street sweepings, although recycling may be possible in some instances. What we see in any of the street waste is that the contaminants are tied to the finer-grained particles. Theoretically, the better job that someone does of sorting the fines out, the better chance there is of them becoming dangerous waste. Still, we simply haven't seen it approach dangerous waste criteria.

World Sweeper: Historically, the street sweeping industry started out sweeping for cosmetics. Now a movement is taking place toward the greater and higher goal of getting the fines out, since that is where the toxic components are. It appears that a contradiction may be appearing: The better job someone does with getting up the more highly polluted fines, which are what is hurting our national water quality, the higher the likelihood that the city or contractor will have trouble disposing of the debris they picked up.

For a contractor, especially: Where's the incentive to do an extra good job, if a possible 'reward' will be having no place to dump, or having to pay more for disposal?

Hepp: Well, it's not that bad around here, although trouble might show up when you try to screen. If all of the coarse stuff is sifted out to go to one place, then the sand sifted out to go someplace else, then what's left over is the real fines and they have a relatively higher pollution concentration. You can't dilute contamination to not become a danger and that is the problem. But, if you never concentrate it then you don't have to worry about it.

Although it may be more applicable to catch basin waste than street sweepings, it is still something that needs to be looked at: If you make a product out of one component of the debris-stream, are you making a dangerous waste out of what's left over? That's a question which hasn't yet been answered very sufficiently.

We are recommending testing only about once a quarter for normal street sweepings. Still, without a requirement, there's no incentive to test even that often. Our basic landfill disposal cost is $80 a ton, which is fairly average around here, and a polycyclic aromati hydrocarbons (PAH) test is $150. So who wants to voluntarily pay $150 a sample for testing when they could plain take it to the landfill for $80 bucks?

People are trying to recycle street waste, but at the present time it seems to not be feasible. We strongly support the recyclability of solid waste, however, and are actively looking at ways to recycle more of catch basin and street waste. Part of recyclability depends upon the schedule and frequency of cleaning, etc.

For now, landfill disposal is probably still the most economic and safe option available. That is what landfills are built for and this material is safe in them. If someone is sweeping a parking area, like a discount store, for example, probably the best thing to do is just dump the sweepings into a dumpster. The volume is not going to be significant, and it shouldn't pose a problem as long as it is dry enough to pass the standard paint filter test. My opinion is that up to around 200 pounds should be able to be added directly to dumpsters, from the site it was picked up, without any problem to waste-hauling equipment.

Ecology has looked at street sweepings and said that it essentially is just trash. Although the concentrations of metals, for example, may be higher than some people like, one thing to remember is that they are not mobile. Anything that was very soluble is gone, into either the runoff or the air. What sweepers pick up off the street is, by and large, what stayed behind.

For more information on the State of Washington Department of Ecology study, contact Michael Hepp at 360-407-6420.

This article is reprinted from American Sweeper magazine, v4 n2.

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